The present invention relates to threshing and more particularly to threshing machines having cylinders.
While the terms "grain" and "straw" are used principally throughout this specification for convenience, it should be understood that the terms are not intended to be limiting. Thus "grain" refers to that part of the crop material which is threshed and separated from the discardable part of the crop material which is referred to as "straw".
With combines at present in use, the operator often wants to have the option to either use or not use a straw chopper. Such a straw chopper often is mounted on the combine strawhood in an "out-of-use" position and is movable manually, when desired, to an "in-use" position. Due to the bulky nature of such a straw chopper, such an operation is often difficult, tiring and time consuming.
In an attempt to overcome this problem, it has already been proposed to attach a straw chopper in a fixed position to the outlet of a combine strawhood, and to install a deflector plate between the straw walkers of the combine and the straw chopper which is adjustable in two positions. In one position of the deflector plate, straw, which drops from the straw walkers, is guided into the chopper, while that in the other position, said straw is guided past the straw chopper and dropped directly onto the ground. However, in such an arrangement, the free opening for the straw to pass through, in case it is not chopped, has been reduced substantially. As a result thereof risks for plugging have increased accordingly. Moreover, as straw is moved across such a deflector plate only by gravity, this is another reason for increased risks for plugging even when the components are adjusted for chopping the straw.
It has been attempted to overcome such plugging risks by installing feed rolls between the straw walkers and the straw chopper and which forcefully feed straw into the straw chopper. However, these feed rolls have no effect on the plugging risks in case the machine is adjusted in the "non-chopping" condition. Moreover, the provision of additional components, such as feed rolls and the drives, therefore, only can increase the total cost price of the machine.
Recent developments in combines have led to the so called "rotary" combines, wherein the oscillatory straw walkers have been replaced by rotary separator components. Also on these machines, a straw chopper may be provided which the operator may not wish to use at all times, but which must be readily available for use when required. If the straw chopper is attached, as on conventional combines, at the rear end of the straw hood, substantially the same problems are present in this combination as in the combination of a conventional combine equipped with a straw chopper.
Furthermore, it is normally necessary that, when the straw chopper is in the "out-of-use" condition, the straw issuing from the machine is discharged onto the ground in a windrow suitable for an eventual subsequent baling operation. On the other hand, when the straw is chopped, such chopped straw should be evenly spread across a wide band whereby subsequent tillage problems will be avoided. This objective has not always been met with the known arrangements.
The foregoing illustrates limitations of the known prior art. Thus, it is apparent that it would be advantageous to provide an alternative directed to overcoming one or more of the limitations as set forth above.